Dotted Slug - Arion circumscriptus circumscriptus


Usually 30-40 mm. This slug belongs to a species complex (Arion fasciatus group) containing the following species: Arion silvaticus, A. circumscriptus and A. fasciatus which are hard to distinguish without dissecting the genitalia, though some visual differences are present - see below. All are greyish centrally and white laterally with a pair of dark-colored longitudinal stripes.However Arion circumscriptus has speckly markings on the mantle and the tentacles and head are black in colour. The pneumostome (breathing pore) occurs in the anterior one-third of the slug's mantle on the right side of the body. In contracted individuals the body is bell-shaped. No keel is present in this group; however, an enlarged row of pale coloured tubercles may create an impression that one may exist (false keel). The sole of this species-complex is pale coloured, similar to the foot fringe and the mucus secreted by this group is colourless or occasionally pale yellow.

Similar Species

Arion circumscriptus - speckles on the mantle + grey flanks below the stripe

Arion silvaticus - pale silver flanks below the stripe

Arion fasciatus - yellow flanks below the stripe

Identification difficulty

A wide range of habitats, and will tolerate damper conditions than some other species.

When to see it

All year.

UK Status

Common though under-recorded due to the similarity with other Arion species.

VC55 Status

Fairly common in Leicestershire and Rutland.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map